Just completed a 4 night stay over Christmas at this property and was very impressed. Check-in was friendly - the front desk staff came and shared their favourite recommendations in Berlin with a smile.
Was unable to apply DSU ~2 months in advance - all booked. Was offered to buy-up + apply DSU to get a larger suite at 125 euro a night - I passed. Was placed on the 7th floor (club level) in a cozy room.
Breakfast at the restaurant is very nice. Staff remembered us each morning and were friendly and pleasant.
Would definitely stay at the Grand Hyatt Berlin again.